Carbon rings, naming

The bivalent radical —NH— linked to two identical radicals can be denoted by the prefix imino-, as well as when it forms a bridge between two carbon ring atoms. A trivalent nitrogen atom linked to three identical radicals is denoted by the prefix nitrilo-. Thus ethylenediaminetetraacetic acid (an allowed exception) should be named ethylenedinitrilotetraacetic acid. 

Aromatic organic chemistry is a special branch of organic chemistry because the six-membered carbon rings that define aromatic compounds are exceptionally stable and act as central supports to which other groups can be attached. The name aromatic was given to early isolated examples of these compounds because they have characteristic odors. 

Class 3 consists of compounds in which two rings are joined by one chemical bond between carbon atoms from each ring. Names of saturated compounds are alkyl-l,l -bicycloalkyls, and alkyltercycloalkyls. Position numbers of the different rings are distinguished by use of primes. Thus,... 

Another tetracyclic carbon skeleton, named cumbiane, has been isolated from Pseudopterogorgia elisahethae. Its representatives are the diterpenoids cumbiasin A (33) and B (34) [20] their structures and relative configurations were elucidated by interpretation of a combination of spectral data. The six-membered ring D was formed by connecting CIO and C16 of an elisabethane carbon skeleton. The carbocyclic skeleton of the cumbiasins is unprecedented and represents a new class of C20 rearranged diterpenes. The tricyclic seco-cumbiane skeleton is derived from the cumbiasins by cleavage of the C15-C16 bond. Due to intramolecular cyclizations two additional oxo-heterocycles are present in cumbiasin C (35) [20] (Fig. 7). 

The chair is not the only conformation that cyclohexane might adopt. An alternative boat conformation is attained if the ring flip-type process is confined to just one carbon. The name boat comes from the similarity to boats formed by paper... 

FIGURE 15.1 Skeletons of a (25)-flavanone and a (27 ,37 )-dihydroflavonol, showing the numbering of the carbons and naming of the rings. 

In hexagonal diamond (wurtzite structure) the wrinkled sheets are stacked in an ABABAB sequence, as shown in the Figure 7. Looking down on the stack from above, hexagonal holes can be seen formed by the six-membered carbon rings. The crystal has hexagonal symmetry about this axis, hence the name hexagonal diamond, or wurtzitic carbon. 

The prefix cyclo- is used to name cycloalkanes. Cyclopropane is planar, but larger carbon rings are puckered. Cyclohexane exists mainly in a chair conformation with all bonds on adjacent carbons staggered. One bond on each carbon is axial (perpendicular to the mean carbon plane) the other is equatorial (roughly in that plane). The conformations can be interconverted by flipping the ring, which requires only bond rotation and occurs rapidly at room temperature for cyclohexane. Ring substituents usually prefer the less crowded, equatorial position. 

Some frameworks of alicyclic compounds are derived from fragments of diamond, as shown in Fig. 14.2.1. In these molecules, all six-membered carbon rings have the chair conformation. Diamantane C14H20 is also named... 

A lactone is an ester in which the functional group of the ester has become part of a ring structure with carbon atoms. Names of lactones end with -in or -one, e.g. umbelliferone. 

The nomenclature applicable to cata-condensed (no atom is common to three or more rings) benzenoid (all carbon rings of size 6) molecules comprised of n rings, that are not also corona-condensed (forms a ring of rings) is one of simplicity and organization. Every member of this set has the same principal part in their name ... 

Write the root -cyclo- plus the name for the number of carbon atoms in the ring. For example, a five-carbon ring would have the root -cyclopent-. 

A special ring compound, the six-carbon ring with three double bonds, is known by its common name benzene (Figure 1.15). This particular arrangement has a... 

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